Issue 10, July 2, 2018

Why Mulch?

There are numerous kinds of mulch that can be used in the landscape from lawn clippings, leaves, pine needles (can make soils more acidic), hay, coco hulls, straw, bark chips, composted bark mulch and even old newspapers. I completely understand that lawn clippings, straw, hay, leaves and newspapers aren't as attractive, but they can easily be used in a garden to keep weeds at bay. Most home or garden stores carry bark chips and composted bark mulch in a variety of colors and sizes. The mulches make for a uniform and neat attractive look to the landscape. There are hardwood mulches and softwood mulches in various sizes and this will dictate how long they will last in the landscape. Organic mulches like these will decompose at different rate and will need to be replenished every 1 to 3 years. There are inorganic mulches available, like rubber rings, pulverized rubber mulch and rocks. These do not decompose and do not need to be replenished but will not help to aid in soil fertility or soil health in the long run. They can also be hard on a window when hurled from a lawn mower. 

Mulch has a lot of benefits for not only the soil but the aesthetics of the landscape. Below is a list of just some of the reasons mulch should be incorporated into a lawn landscape design.

Advantages to Mulching

  • Protects the soil from erosion
  • Conserves soil moisture loss through evaporation
  • Suppresses weed germination and growth
  • Can improve soil health, as the mulches decomposes it will turn into fertilizer as well as help with soil structure and drainage over time.  
  • Mulch makes for a great insulator of the soil in the winter keeping plant's roots warmer and cooler in the summer.
  • With the ability to control moisture, a layer of mulch can inhibit certain plant diseases.
  • Mulch is also pretty- giving landscape a uniform and manicured look.

When is enough, enough?

As beneficial as mulch is, too much can be harmful. It is recommended to mulch to a depth of 2 to 4 inches. Unfortunately the saying "more is better" does not stand true when mulching around trees as there are many trees that fall victim to volcano mulching. Having too deep of mulch can allow for other micro climates to develop that are conducive for destructive diseases and insects. Since most organic mulches decompose at different rates, it is important to check the depth of the mulch before just adding or top dressing your landscape.

Improper mulching volcano.

Disadvantages of too much mulch

  • "Volcano mulching" the trunks of young trees may create habitats for rodents that chew the bark and can girdle the trees.
  • Deep mulch can lead to excess moisture in the root zone, which can stress the plant and cause root rot.
  • Piling mulch against the trunk or stems of plants can stress stem tissues and may lead to insect and disease problems.
  • Depending on the type of mulch (pine needles) will cause the soil pH to change
  • Continued use of certain mulches over long periods can lead to micronutrient deficiencies or toxicities.
  • Fine mulches could become matted and actually prevent water from leaching down to the root zone. It also can be a good environment for weed seeds to germinate.
  • Anaerobic "sour" mulch may give off pungent odors, and the alcohols and organic acids that build up may be toxic to young plants.

 This is a good time to be refreshing your landscape beds or creating new landscaped areas in yards. As you are putting down mulch, be sure to check the depth before adding any new and be sure to make sure you are putting mulch down into a clean bed. Listed below are great resources on mulching. (Maria Turner)

Maria Turner

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